The invention generally relates to forming a layer on a flow plate of a fuel cell stack.
A fuel cell is an electrochemical device that converts chemical energy that is produced by a reaction directly into electrical energy. For example, one type of fuel cell includes a polymer electrolyte membrane (PEM), often called a proton exchange membrane, that permits only protons to pass between an anode and a cathode of the fuel cell. At the anode, diatomic hydrogen (a fuel) is reacted to produce hydrogen protons that pass through the PEM. The electrons produced by this reaction travel through circuitry that is external to the fuel cell to form an electrical current. At the cathode, oxygen is reduced and reacts with the hydrogen protons to form water. The anodic and cathodic reactions are described by the following relationships:H2→2H++2e−  Eq. 1at the anode of the cell, andO2+4H++4e−→2H2O  Eq. 2at the cathode of the cell.
A typical fuel cell has a terminal voltage near one volt DC. For purposes of producing much larger voltages, several fuel cells may be assembled together to form a fuel cell stack, an arrangement in which the fuel cells are electrically coupled together in series to form a larger DC voltage (a voltage near 100 volts DC, for example) and to provide more power.
The fuel cell stack may include flow plates (graphite composite or metal flow plates, as examples) that are stacked one on top of the other, and each flow plate may be associated with more than one fuel cell of the stack. The flow plates may include various surface flow channels and orifices to, as examples, route the reactants and products through the fuel cell stack. Several PEMs (each one being associated with a particular fuel cell) may be dispersed throughout the stack between the anodes and cathodes of the different fuel cells. Electrically conductive gas diffusion layers (GDLs) may be located on each side of each PEM to form the anode and cathodes of each fuel cell. In this manner, reactant gases from each side of the PEM may leave the flow channels and diffuse through the GDLs to reach the PEM.
The electrochemical reactions inside the fuel cell stack produce heat that must be removed from the stack. Thus, a coolant may be circulated through the stack to absorb thermal energy from the stack and carry this thermal energy away from the stack. There are a wide variety of potential coolants available. However, the coolants that may be used depend on various properties of the fuel cell stack.
Thus, there exists a continuing need for an arrangement and/or technique to expand the different types of coolants that may be used in connection with the operation of a fuel cell stack.